A uniform lower bound on weights of perceptrons

  • Authors:
  • Vladimir V. Podolskii

  • Affiliations:
  • Moscow State University

  • Venue:
  • CSR'08 Proceedings of the 3rd international conference on Computer science: theory and applications
  • Year:
  • 2008

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Abstract

A threshold gate is a linear function of input variables with integer coefficients (weights). It outputs 1 if the value of the function is positive. The sum of absolute values of coefficients is called the total weight of the threshold gate. A perceptron of order d is a circuit of depth 2 having a threshold gate on the top level and conjunctions of fan-in at most d on the remaining level. For every n and d ≤ D ≤ ∈n1/6 we construct a function computable by a perceptron of order d but not computable by any perceptron of order D with total weight 2o(nd/D4d). In particular, if D is a constant, our function is not computable by any perceptron of order D with total weight 2o(nd). Previously functions with this properties were known only for d = 1 (and arbitrary D) [2] and for D = d [12].